PTB-Berichte Elektrizität (PTB-E)
Publikations Einzelansicht
Bericht
| Titel: |
High frequency thin-film thermal converter on a quartz crystal chip |
| Autor(en): |
L. Scarioni |
| Editor: |
Physikalisch-Technische Bundesanstalt |
| Report Typ: |
PTB-Bericht |
| Jahr: |
2003 |
| Dokument Nummer: |
PTB-E-83 |
| Seite(n): |
128 , 75 Abb., 24 Tab |
| Verschiedenes: |
€ 18,50 |
| ISBN: |
ISBN 978-3-86509-046-1 |
| Schlüsselwörter: |
PTB-E- |
| Zusammenfassung: |
Thermal converters are the most accurate devices used by National Metrology Institutes for the transfer of ac voltage and current to equivalent dc quantities. Today, thin-film or planar multijunction thermal converters are employed in the frequency range from 10 Hz up to 1 MHz with uncertainties between 1 .my.V/V to 13 .my.V/V.
For frequencies above 100 kHz the ac-dc transfer difference of the standard thin-film or planar multijunction thermal converter (PMJTC) developed at the PTB and fabricated on a silicon chip show an increase towards negative values for high heater resistances. A model that explains the behaviour of the thin-film converter on a silicon chip at high frequencies was developed. This model shows that an improvement in performance in this frequency range is possible by the change of the geometry of the bonding pads of the heater.
To imporve the standards for the measurement of the ac-dc transfer difference in the range from 100 kHz up to 100 MHz, a new thin-film multijunction thermal converter on a quartz membrane and a quartz chip has been developed. The window with the membrane for the converter was anisotropically etched into the quartz crystal chip and the structure of the bifilar heater and the thermocouples was fabricated using standard photolithographic procedures. The converters fabricated show ac-dc transfer differences below 5 .my.V/V in the frequency range from 100 kHz to 1 MHz. this is a reduction of more than one order of magnitude of the ac-dc voltage transfer difference in comparison to the PMJTC with an Si.sub.3.nosub.N.sub.4.nosub./SiO.sub.2.nosub./Si.sub.3.nosub.N.sub.4.nosub. sandwich membrane on a silicon chip. An electrical model taking all sources of ac-dc transfer differences at high frequencies into account was developed. A comparison of the results of simulations with those of measurements for converters with different heater resistances show good agreement. Therefore, the model can be used for the optimisation of the converter at high frequencies. The uncertainty of this model was calculated.
A further improvement of the frequency response of the new thermal converter in the range of 10 MHz to 100 MHz has been achieved. By using a built-in Tee structure the ac-dc transfer difference in the range from 10 MHz to 100 MHz decrease by a factor of 10.
The decrease of the ac-dc difference allows to decrease the uncertainty of the PTB ac-dc transfer standards, using the developed model for the uncertainty analysis. |
| Bemerkung: |
High frequency thin-film thermal converter on a quartz crystal chip ; (PTB-Bericht PTB-E-83) ; Zugl.: Braunschweig, Technische Univ., Diss., 2003 |
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